Method and apparatus for transmitting and receiving resource allocation information in a wireless communication system

ABSTRACT

A method and an apparatus for transmitting and receiving resource allocation information in a wireless communication system are provided. The method includes allocating resources for each of one or more device-to-device (D2D) discovery resources pools, generating information related to resources allocated for each of the one or more D2D discovery resource pools, and transmitting the generated information.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a U.S. National Stage application under 35 U.S.C.§371 of an International application filed on Aug. 7, 2014 and assignedapplication number PCT/KR2014/007310, which claimed the benefit of anIndian patent application filed on Aug. 7, 2013 in the Indian patentOffice and assigned Serial number 933/KOL/2013, of an Indian patentapplication filed on Oct. 21, 2013 in the Indian patent Office andassigned Serial number 1195/KOL/2013, of an Indian patent applicationfiled on Jan. 22, 2014 in the Indian patent Office and assigned Serialnumber 95/KOL/2014, and of an Indian patent application filed on Mar.18, 2014 in the Indian patent Office and assigned Serial number340/KOL/2014, the entire disclosure of each of which is herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus fortransmitting and receiving resource allocation information in a wirelesscommunication system.

BACKGROUND

Device-to-Device (D2D) discovery is a process of determining whether auser equipment (UE) that is capable of D2D communication (hereinafter,referred to as D2D-enabled UE) is in proximity of another D2D-enabledUE. Discovery of a D2D-enabled UE comprises determining whether anotherD2D-enabled UE is of interest to it using D2D discovery. A D2D-enabledUE is of interest to a discovering D2D-enabled UE if its proximity needsto be known by one or more authorized applications in the discoveringD2D-enabled UE.

For example, a social networking application may be enabled to use D2Ddiscovery features. The D2D discovery enables the D2D-enabled UE of agiven user of a social networking application to discover and bediscoverable by the D2D-enabled UEs of his/her friends. In anotherexample, the D2D discovery may enable the D2D-enabled UE of a given userof a search application to discover stores or restaurants of interest inits proximity.

A D2D-enabled UE may discover other D2D-enabled UEs in its proximity byusing direct UE-to-UE signaling with evolved universal terrestrial radioaccess (E-UTRA) technology. This is referred as D2D direct discovery.Alternatively, a communication network determines the proximity of twoD2D-enabled UEs and informs them of their proximity. This is referred asnetwork-assisted D2D discovery.

It is assumed that the same spectrum or radio frequency is used for D2Ddiscovery and regular communication between a UE and a base station(BS). In traditional communication, a UE and a BS communicate with eachother by establishing a connection with each other and the BS allocatesdedicated resources to the UE.

In the case of D2D discovery, the requirements are quite different.There is no one-to-one communication between a D2D-enabled UEtransmitting discovery information and another D2D-enabled UE receivingthe discovery information during D2D direct Discovery. The discoveryinformation transmitted by the D2D-enabled UE may be received andprocessed by multiple D2D-enabled UEs. D2D discovery is a continuousprocess performed by the D2D-enabled UEs. The D2D-enabled UEs should beable to perform D2D discovery irrespective of their states (that is,idle or connected). During the D2D direct discovery, the D2D-enabled UEmonitoring the discovery information should know time and frequencyresources used by the D2D-enabled UE transmitting the discoveryinformation. The D2D discovery should coexist with legacy UE-BScommunication. The time and frequency resources configured for discoveryshould minimize impact on legacy UEs. For example, latency-sensitiveapplications of legacy UEs should not be affected. That is, asynchronous hybrid automatic repeat request (HARQ) operation on anuplink (UL) should not be affected.

Accordingly, there is a need for a method for configuring and signalingresources for D2D discovery.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

An aspect of the present disclosure is to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide a method and apparatus for transmitting andreceiving resource allocation information in a wireless communicationsystem.

Another aspect of the present disclosure is to provide a method andapparatus for configuring and signaling resources for device-to-device(D2D) discovery.

Another aspect of the present disclosure is to provide a method andapparatus for enabling D2D discovery without affecting communication oflegacy user equipments (UEs) and an uplink (UL) hybrid automatic repeatrequest (HARQ) operation.

In accordance with an aspect of the present disclosure, a method of abase station (BS) in a communication system, the method comprising:generating information related to resources for discovery, theinformation includes subframe bitmap information; and transmitting theinformation. In accordance with another aspect of the presentdisclosure, a method of a user equipment (UE) in a communication system,the method comprising: receiving information related to resources fordiscovery, the information includes subframe bitmap information; andperforming discovery based on the information.

In accordance with another aspect of the present disclosure, a basestation (BS) in a communication system, the BS comprising: at least oneprocessor configured to generate information related to resources fordiscovery, the information includes subframe bitmap information, and atransceiver configured to transmit the information.

In accordance with another aspect of the present disclosure, a userequipment (UE) in a communication system, the UE comprising: atransceiver configured to receive information related to resources fordiscovery, the information includes subframe bitmap information, and atleast one processor configured to perform discovery based on theinformation.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates a discovery resource configuration according to anembodiment of the present disclosure;

FIGS. 2A-2D illustrate radio resource configurations for a subframe fordirect discovery according to various embodiments of the presentdisclosure;

FIGS. 3A and 3B illustrate guard bands between resources fordevice-to-device (D2D) discovery and resources for communication betweena base station (BS) and a user equipment (UE) according to variousembodiments of the present disclosure:

FIGS. 4A-4E illustrate subframe patterns for a discovery resourceinterval (DRI) according to various embodiments of the presentdisclosure;

FIGS. 5A and 5B illustrate usages of subframe patterns in a DRIaccording to various embodiments of the present disclosure;

FIGS. 6A and 6B illustrate partial usages of subframe patterns in a DRIdue to a DRI size according to various embodiments of the presentdisclosure;

FIG. 7 illustrates a discovery resource configuration using a physicaldownlink control channel (PDCCH) according to various embodiments of thepresent disclosure;

FIG. 8 illustrates a discovery resource configuration using a PDCCHtransmitted a plurality of times according to various embodiments of thepresent disclosure;

FIG. 9 illustrates a discovery resource configuration using a PDCCHbased on a discontinuous reception (DRX) cycle according to variousembodiments of the present disclosure;

FIG. 10 illustrates a discovery resource configuration using a PDCCHbased on a DRX cycle according to various embodiments of the presentdisclosure;

FIG. 11 illustrates a discovery resource configuration using a systeminformation (SI) message and a PDCCH according to various embodiments ofthe present disclosure;

FIG. 12 illustrates a discovery resource configuration using an SImessage and a PDCCH according to various embodiments of the presentdisclosure;

FIG. 13 illustrates a discovery resource configuration using an SImessage and a PDCCH according to various embodiments of the presentdisclosure;

FIG. 14 illustrates a discovery resource configuration using an SImessage and a PDCCH according to various embodiments of the presentdisclosure;

FIG. 15 is a flowchart illustrating an operation of a BS according tovarious embodiments of the present disclosure;

FIG. 16 is a flowchart illustrating an operation of a UE according tovarious embodiments of the present disclosure;

FIG. 17 is a block diagram of a BS according to various embodiments ofthe present disclosure; and

FIG. 18 is a block diagram of a UE according to various embodiments ofthe present disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

By the term “substantially” it is meant that the recited characteristic,parameter, or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to those ofskill in the art, may occur in amounts that do not preclude the effectthe characteristic was intended to provide.

It is to be noted that the concepts of device-to-device (D2D) discoveryaccording to the present disclosure are applicable to any type of D2Dcommunication (discovery signal transmission and reception or datatransmission and reception).

Discovery Resource Configuration

In an embodiment of the present disclosure, radio resources for directdiscovery are allocated or reserved periodically. For this purpose,discovery resources are configured as illustrated in FIG. 1 according toan embodiment of the present disclosure.

FIG. 1 illustrates a discovery resource configuration according to anembodiment of the present disclosure.

Referring to FIG. 1, the periodicity of reserving or allocatingdiscovery resources may be indicated by a discovery resource cycle (DRC)100. The DRC 100 includes a discovery resource interval (DRI) 102 and anon-discovery resource interval 104. Discovery resources are allocatedor reserved for a duration indicated by the DRI 102 in every DRC 100.The DRC 100 and the DRI 102 are common for all D2D-enabled userequipments (UEs). In an embodiment, the DRC 100 and/or the DRI 102 arecommon for a group of D2D-enabled UEs.

In an embodiment, all subframes 106 of the DRI 102 may be allocated orreserved for direct discovery. In an embodiment, a subframe comprises atime slot of 1 ms duration. In another method, selective subframes 108of the subframes of the DRI 102 may be allocated or reserved for directdiscovery. Reservation or allocation of several consecutive subframesfor direct discovery may affect latency-sensitive traffic for legacyUEs.

FIGS. 2A-2D illustrate radio resource configurations for a subframe fordirect discovery according to various embodiments of the presentdisclosure.

Radio resources of a subframe for direct discovery may be configured andused in various manners according to various embodiments of the presentdisclosure. For example, all resources (for example, radio blocks (RBs))of a subframe indicated for direct discovery may be used for directdiscovery as illustrated in FIG. 2A.

In another example, resources except physical uplink common controlchannel (PUCCH) resources of a subframe indicated for direct discoverymay be used for direct discovery as illustrated in FIG. 23B.Alternatively, resources except PUCCH and physical random access channel(PRACH) resources of a subframe indicated for direct discovery may beused for direct discovery.

In another example, discovery subframe resources (other than PUCCHresources and/or PRACH resources) may also be shared with legacy UEcommunication, as illustrated in FIGS. 2C and 2D. The legacy UEcommunication refers to communication between a UE and a BS. In thiscase, a discovery resource configuration indicates not only subframe(s)for discovery in a DRC but also indicates which resources (i.e. RBs) ineach of the indicated discovery subframe(s) are meant for discovery, orindicates which resources in each of the indicated discovery subframe(s)are not meant for discovery.

Guard Band Between Discovery Resources and Resources for CommunicationBetween UE and BS

If a subframe includes discovery resources as well as resources forUE-BS communication, transmissions from a D2D-enabled UE in thediscovery resources may affect or interfere with transmissions in theresources for UE-BS communication. Even if the discovery resources andthe resources for UE-BS communication are different, the transmissionsof the D2D-enabled UE may not be power-controlled, thus causing spuriousemissions. In this context, a guard band is defined between D2Ddiscovery resources and resources for UE-BS communication in anembodiment of the present disclosure.

FIGS. 3A and 3B illustrate guard bands between resources for (D2D)discovery and resources for UE-BS communication according to variousembodiments of the present disclosure.

According to an embodiment of the present disclosure, a guard band maybe disposed between PUCCH resources and discovery resources adjacent tothe PUCCH resources, as illustrated in FIG. 3A. The size of the guardband (for example, the number of RBs) may be fixed or determined by thenetwork.

A D2D-enabled UE determines the PUCCH resources (that is, RBs) using aPUCCH resource configuration signaled in a system information (SI)message by a BS and skips the discovery resources corresponding to theguard band adjacent to the PUCCH resources. The D2D-enabled UE may notuse the discovery resources corresponding to the guard band intransmitting discovery information.

Meanwhile, the resources corresponding to the guard band may not beindicated as discovery resources in a discovery resource configurationby the BS. This guard band may also be defined between resources forUE-BS communication and discovery resources, as illustrated in FIG. 3B.

Selective Discovery Subframe Pattern

If all subframes of a DRI are not allocated for discovery, a subframepattern is needed for the DRI.

FIGS. 4A-4E illustrate subframe patterns for a DRI according to variousembodiment of the present disclosure. For example, four subframepatterns are illustrated in FIGS. 4A-4E and subframes may be configuredin the DRI in one of the four subframe patterns.

In pattern 1, as illustrated in FIG. 4A, one subframe (SF) 400 forlegacy communication is followed by ‘T’ subframes 402 for discovery.Herein, ‘T’ is a retransmission interval between hybrid automatic repeatrequest (HARQ) packets. It is to be noted that the legacy SF refers toan SF which is used for UE-BS communication. A retransmission interval408 is illustrated in FIG. 4C.

In pattern 2, as illustrated in FIG. 4B, ‘p’ SFs 404 for legacycommunication are followed by ‘T−p+1’ SFs 406 for discovery. Herein, ‘T’is a retransmission interval between HARQ packets and ‘p’ is an integergreater than zero. Pattern 1 may be regarded as a special case ofpattern 2. If ‘p’ is set to 1, pattern 2 becomes pattern 1.

Referring to FIGS. 4D and 4E, pattern 3 and pattern 4 are the same aspattern 1 and pattern 2 except that ‘T’ SFs 410 and ‘T−p+1’ SFs 414 fordiscovery are followed by an SF 412 and ‘p’ SFs 416 for legacycommunication in pattern 3 and pattern 4, respectively.

SFs for legacy communication and SFs for D2D discovery may be easilyidentified in a DRI by knowing a pattern type (for example, pattern 2 orpattern 4) and parameters ‘T’ and ‘p’. In an embodiment, the value of‘p’ may be dynamically changed based on discovery load and legacy UEload. It is to be noted that legacy UE load refers to the load of UE-BScommunication. The subframe pattern type (for example, pattern 1 andpattern 2 or pattern 3 and pattern 4) may be configured in a static,semi-static, or dynamic manner.

FIGS. 5A and 5B illustrate usages of patterns in a DRI according tovarious embodiment of the present disclosure.

FIG. 5A illustrates a case in which pattern 1 is used in a DRI and FIG.5B illustrates a case in which pattern 2 is used in a DRI. Aretransmission interval of 6 SFs is used in these examples of FIGS. 5Aand 5B.

FIGS. 6A and 6B illustrate examples in which partial SF patterns areused in a DRI because of the size of the DRI according to variousembodiment of the present disclosure.

The DRI size is not a multiple of the number of SFs in each pattern. InFIG. 6A, pattern 1 is repeated twice and a third repetition containsonly partial D2D SFs 600. Referring to FIG. 6B, pattern 2 is repeatedonce and a second repetition contains only legacy SFs 620.

The patterns described above may be signaled as follows.

a) A parameter ‘NumNonDiscoverySF’ indicates non-discovery subframes infirst ‘N’ subframes at the beginning of a DRC or spaced from thebeginning of the DRC by a specific offset. The parameter‘NumNonDiscoverySF’ may indicate an absolute number of subframes. Among‘N’ subframes, NumNonDiscoverySF may indicate the number of consecutivenon-discovery subframes at the beginning of the ‘N’ subframes or at theend of the ‘N’ subframes. The value of N may be equal to an HARQretransmission interval or an HARQ round trip time (RTT) or any othervalue configurable by a network. In one example, the value of N may be8. In another example, the value of N may be 10 subframes (that is, oneradio frame). The value of N can be different for a time division duplex(TDD) and frequency division duplex (FDD) system. In an embodiment,subframes periodically occurring at an HARQ retransmission interval oran HARQ RTT from each of the indicated non-discovery subframes may benon-discovery subframes in the DRI. In another method, the pattern ofdiscovery and non-discovery subframe signaled for first ‘N’ subframes(using parameter ‘NumNonDiscoverySF’ explained above) is repeated untilthe end of DRI if DRI duration is signaled explicitly. Alternately, thepattern of discovery and non-discovery subframe signaled for first ‘N’subframes (using parameter “NumNonDiscoverySF” explained above) isrepeated ‘NumRepetition’ times wherein ‘NumRepetition’ is indicated inresource configuration signaling. In this case, DRI is equal to‘N*NumRepetition’ and is not explicitly signaled.

b) Alternatively, ‘NumNonDiscoverySF’ may be a bitmap of size N bits, inwhich each bit corresponds to a subframe/frame and indicates whetherthat subframe/frame is a discovery subframe/frame. In an embodiment, themost significant bit of the bitmap corresponds to a first subframe/framein the DRC and the least significant bit of the bitmap corresponds to anNth subframe/frame in the DRC. In another method, the least significantbit of the bitmap corresponds to a first subframe/frame in the DRC andthe most significant bit of the bitmap corresponds to an Nthsubframe/frame in the DRC. The value of N is equal to an HARQretransmission interval, an HARQ RTT, a DRI, or any other valueconfigurable by a network. The value of N can be different for a TDD andFDD system. In one example, the bitmap may be 8 or 10 bits or othermultiples of 8 or 10. In an embodiment, subframes periodically occurringat an HARQ retransmission interval or an HARQ RTT from each of theindicated non-discovery subframes may be non-discovery subframes in theDRI. In another method, the pattern of discovery and non-discoverysubframe signaled for first ‘N’ subframes using bitmap(‘NumNonDiscoverySF’) is repeated until the end of DRI if DRI durationis signaled explicitly. Alternately, the pattern of discovery andnon-discovery subframe signaled for first ‘N’ subframes is repeated‘NumRepetition’ times wherein ‘NumRepetition’ is indicated in resourceconfiguration signaling. In this case DRI is equal to ‘N*NumRepetition’and is not explicitly signaled. Alternately, the pattern of discoveryand non-discovery subframe signaled for first ‘N’ subframes is notrepeated. In this case, DRI is equal to ‘N’. A set of sizes of N can bedefined. For example, the set of sizes of N may be {144, 168}. Thebitmap comprising discovery resource configuration will be one of thesizes in the set. For FDD, the bitmap refers to the contiguous set ofsub-frames starting from the first subframe in DRC. For TDD, the bitmaprefers to the contiguous set of sub-frames starting from the firstsubframe in DRC. Alternately, for TDD, the bitmap refers to allsub-frames of a radio frame except sub-frames 0, 1, 5 and 6. Note thateach radio frame has 10 subframes numbered from 0 to 9.

Determining Start of DRC

In an embodiment of the present disclosure, a start of a DRC may bedetermined to be a system frame number (SFN) which satisfies ‘SFN modDRC=zero’ (herein, DRC is the duration of a DRC in frames).Alternatively, an SFN which satisfies ‘SFN mod DRC=offset’ (herein, DRCis the duration of a DRC in frames) may be the start of the DRC. Offsetmay be any integer in the SFN. The offset may be signaled along with adiscovery resource configuration.

In another embodiment, DRC starts at a subframe number ‘sub FN’ in anSFN where a DRC starts satisfies ‘(SFN*10+sub FN) mod DRC=offset’ (DRCis the duration of a DRC in subframes and the offset is also specifiedin subframes). Each SFN may have 10 subframes numbered from 0 to 9.

In another embodiment, an ‘n’ bit SFN may be extended by ‘x’ bits. Themost significant bit of extended SFN may be broadcasted along withdiscovery resource configuration or broadcasted in other SI.Alternately, the most significant bit of extended SFN may be broadcastedalong with discovery resource configuration or broadcasted in other SIif the DRC is longer than 2^(n) frames. For example, consider that n isequal to 10 bits. This means that SFN can have value from 0 to 1023. Ifthe DRC is 4096 frames then SFN of size 12 bits is needed. The two MSBsof extended SFN are broadcasted along with discovery resourceconfiguration. UE determines the extended SFN by appending the MSBsreceived to regular SFN bits. If the additional MSBs are broadcasted,the UE shall use the extended SFN, otherwise regular SFN is used todetermine the start of DRC in the equations (‘SFN mod DRC=offset’ or‘(SFN*0+sub FN) mod DRC=offset’) explained above.

In another embodiment, if the discovery resource configuration issignaled in time ‘t’ then an offset with respect to time ‘t’ can beprovided in discovery resource configuration. The time ‘t’+offsetindicates the start of DRC. The ‘t’ can be a frame or subframe in whichdiscovery resource configuration is signaled. Alternately the ‘t’ can bethe frame/subframe corresponding to the end of SI window in which thediscovery resource configuration is broadcasted. The offset can also bein units of frame or subframes. The offset can be positive as well asnegative. This method does not require UE to use SFN.

In an embodiment, the offset value, DRC, the DRI and/or parameters forsignaling discovery and non-discovery subframe in DRC may be the samefor all cells with overlapping discovery resources in the network. Inthis case, frames and SFNs may be synchronized across the cells. Anindicator may be transmitted in the signaling of the discovery resourceconfiguration, which indicates whether the discovery resources areoverlapping (that is, the same across all cells). In another embodiment,frame boundaries may be synchronized and SFNs may not be synchronizedacross the cells, so that aligned discovery resource cycle offsets maybe set to different values in different cells.

In another embodiment, adjacent cells may have different offsets so thattheir DRIs (or discovery subframes/resources) may not overlap. A cellshould select an offset in such a manner that its DRI (or discoverysubframes/resources) may not overlap with the DRIs of neighbor cells.This will help a D2D-enabled UE to perform inter-cell discovery withoutskipping the DRI of a camped cell. The cell may also transmit theoffsets and/or DRIs and/or parameters for signaling discovery andnon-discovery subframe in DRC of the neighbor cells to assist the UE ininter-cell discovery.

In another embodiment, a set ‘X’ of discovery resources may beconfigured every DRC. A cell uses a subset of the set ‘X’ for discoverysignal transmission in its coverage. Adjacent cells coordinate with eachother so that subsets of the set ‘X’ selected by the cells may notoverlap with each other. The cell signals the set ‘X’ and set ‘Y’ as asubset of ‘X’ used for discovery resources by the cell. A transmittingUE uses the resources in the set ‘Y’ for transmitting discoveryinformation. A receiving UE uses the resources in the set ‘X’ forreceiving discovery information.

In another embodiment in which cells are not synchronized with eachother at radio frame and subframe levels, the cells may use an absolutesystem time to coordinate with each other so that the DRI of a cell maynot overlap with the DRIs of its neighbor cells or may overlap as muchas possible with the DRIs of its neighbor cells.

In an embodiment of the present disclosure, a cell may indicate whetherits neighbor cells are synchronized with the cell.

Signaling Discovery Resource Configuration

In an embodiment of the present disclosure, a discovery resourceconfiguration is broadcast to D2D-enabled UEs. The discovery resourceconfiguration is broadcast in one or more of the following methods.

a) The discovery resource configuration is broadcast using a new systeminformation block (SIB) in a SI message.

b) The discovery resource configuration is broadcast using a newdownlink control information (DCI) format on a physical downlink commoncontrol channel (PDCCH). The cyclic redundancy check (CRC) of the PDCCHcarrying this new DCI format may be masked with a D2D cell radio networktemporary identifier (C-RNTI). The D2D C-RNTI is a new C-RNTI reservedto indicate resources for direct discovery.

c) The discovery resource configuration is broadcast using a new message(that is, a discovery resource message) transmitted in a downlink sharedchannel (DL-SCH) region. A PDCCH indicating resources for this messagein the DL-SCH region may be masked with a D2D C-RNTI. The D2D C-RNTI isa new C-RNTI reserved to indicate resources for direct discovery.

Some of the parameters in the discovery resource configuration may bestatic in nature and other parameters may be dynamic in nature. Forexample, once configured, the periodicity of discovery resourceallocation, that is, a DRC is not required to be changed. A DRI may haveto be updated in the DRC to take care of the discovery load (the numberof UEs participating in discovery and discovery signals transmitted bythem). In an embodiment, if the DRI is configured in correspondence withthe discovery load of the worst case in a cell, updating the DRI may beavoided. However, if the discovery load is low in the cell, this willlead to resource waste. Subframes designated as discovery subframes inthe DRI may need to be updated based on the current usage of resourcesof UEs for UE-BS communication.

In an embodiment, the discovery resource configuration is broadcastusing a new SIB, a PDCCH, or a discovery resource message. One or morediscovery resource pools may be signaled by the BS as part of discoveryresource configuration. The signaling of each of one or more discoveryresource pools in the discovery resource configuration includes one ormore of the following parameters:

DRC Duration;

DRI Duration;

Discovery subframe indication: all or part;

Discovery subframe bitmap and/or number of repetition of bitmap if DRIduration is not signaled;

Discovery subframe pattern info (that is, pattern 2 or 4 and the valueof ‘p’); and

Discovery channel indices in each subframe, RB indices which arereserved for discovery, or RB indices which are not meant for discovery.

-   -   ‘StartPIBIndex’ and ‘EndPIBIndex’ can be signaled to indicate        discovery RBs in a discovery subframe. One or multiple sets of        ‘StartPRBIndex’ and ‘EndPRBIndex’ can be signaled to indicate        discovery RBs in a discovery subframe. For example, in an        embodiment two sets, ‘StartPRBIndex1’ and ‘EndPRBIndex1’, and        ‘StartPRBIndex2’ and ‘EndPRBIndex2’ can be signaled. Parameters        ‘StartPRBIndex’ and ‘EndPIBIndex’ can be signaled for each        discovery subframe. Alternately they are signaled only for one        discovery subframe and the same is applied for all discovery        subframes. Discovery transmissions on a sub-frame can occur only        on the physical resource block (PRB) index greater than or equal        to ‘StartPRBIndex’. Discovery transmissions on a sub-frame can        occur only on the PRB index lesser than or equal to        ‘EndPRBIndex’. Parameters which may be used for discovery        resource configuration include the following:

Discovery category for each discovery subframe or discovery channelindices;

DRC offset; and

Pattern

Some of the combinations of these parameters, which may be used for adiscovery resource configuration, are as follows:

Option 1:

-   -   DRC Duration    -   DRI Duration

Option 2:

-   -   DRC Duration    -   DRI Duration    -   Discovery channel indices in each subframe, RB indices which are        reserved for discovery, or RB indices which are not meant for        discovery

Option 3:

-   -   DRC Duration    -   DRI Duration    -   Discovery subframe indication: all or part    -   Discovery subframe bitmap or discovery subframe pattern info        (that is, pattern 2 or 4 and the value of ‘p’) and/or number of        repetition of bitmap if DRI duration is not signaled

Option 4:

-   -   DRC Duration    -   DRI Duration    -   Discovery subframe indication: all or part    -   Discovery subframe bitmap or discovery subframe pattern info        (that is, pattern 2 or 4 and the value of ‘p’) and/or number of        repetition of bitmap if DRI duration is not signaled    -   Discovery channel indices in each subframe, RB indices which are        reserved for discovery, or RB indices which are not meant for        discovery.        -   ‘StartPRBIndex’ and ‘EndPRBIndex’ can be signaled to            indicate discovery RBs in a discovery subframe. One or            multiple sets of ‘StartPRBIndex’ and ‘EndPRBIndex’ can be            signaled to indicate discovery RBs in a discovery subframe.            Parameters ‘StartPRBIndex’ and ‘EndPRBIndex’ can be signaled            for each discovery subframe. Alternately they are signaled            only for one discovery subframe and the same is applied for            all discovery subframes.    -   Preferred Option: Discovery resource pool is signaled using the        following parameters. One or more pools may be signaled.        -   DRC Duration        -   DRI Duration (This is optional. Not needed if NumRepetition            is there)        -   DRC Offset        -   Discovery channel indices in each subframe, RB indices which            are reserved for discovery, or RIB indices which are not            meant for discovery, ‘StartPRBIndex’ and ‘EndPRBIndex’ can            be signaled to indicate discovery RBs in a discovery            subframe. One or multiple sets of ‘StartPRBIndex’ and            ‘EndPRBIndex’ can be signaled to indicate discovery RBs in a            discovery subframe. Parameters ‘StartPRBIndex’ and            ‘EndPRBIndex’ can be signaled for each discovery subframe.            Alternately, they are signaled only for one discovery            subframe and the same is applied for all discovery            subframes.            -   Discovery subframe bitmap Length (‘N’) and corresponding                bitmap            -   Number of repetition of bitmap (‘NumRepetition’) (This                is optional. Not needed if DRI duration is there)            -   Type of resources (Type 1 or Type 2 or common)            -   Pool may be a transmission (TX) pool or a reception (RX)                pool

Each of the options mentioned above may also include a DRC offset andother combinations may be used as well. In an embodiment, discoverycategories may be different for different DRCs. For example, an odd DRCmay be used for open direct discovery whereas an even DRC may be usedfor restricted direct discovery. A specific DRC for a specific discoveryresource category may be indicated.

In an embodiment of the present disclosure, a DRI duration may beconfigured to be equal to a DRC duration. In this case, selectivesubframes for discovery are indicated in the DRC. In this case, the DRCduration is signaled. The discovery subframe bitmap or discoverysubframe pattern info (that is, pattern 2 or 4 and the value of ‘p’) isalso signaled. Additionally, discovery channel indices in each subframe,RB indices which are reserved for discovery, or RB indices which are notmeant for discovery are also signaled.

In another embodiment of the present disclosure, a DRC and a DRI may beconfigured to be multiples of a cell-specific discontinuous exception(DRX) cycle. In this embodiment, a UE which is interested intransmitting discovery information in the DRI transmits discoveryinformation in a subframe of the DRI which corresponds to its pagingoccasion in its DRX cycle.

Signaling Discovery Resource Configuration Using PDCCH

In an embodiment of the present disclosure, a discovery resourceconfiguration may be signaled on a PDCCH. If SI needs to be dynamically(or semi-statically) configured, the PDCCH has an advantage over anSIB-based approach.

FIG. 7 illustrates a discovery resource configuration using a PDCCHaccording to an embodiment of the present disclosure.

Referring to FIG. 7, PDCCHs 700 and 710 carrying discovery resourceinformation are transmitted every discovery resource information cycle750. The PDCCHs 700 and 710 indicate the sizes of DRIs 720 and 740 anddiscovery resources included in the DRIs 720 and 740. A PDCCH CRC may bemasked with a D2D C-RNTI. The discovery resource information cycle 750is equal to a DRC.

A DRC 760 may start after an offset 730 from the beginning of thediscovery resource information cycle 750. The offset 730 is needed toallow a time to receive and process PDCCH information, select resourcesfor discovery information transmission, and build a discoveryinformation packet. The DRC 760 may be configured using a PDCCH or an SImessage. In this case, PDCCH monitoring for discovery resourceinformation may be independent of a UE's idle mode DRX cycle.

A D2D-enabled UE wakes up at the beginning of the discovery resourceinformation cycle 750 and receives and decodes a PDCCH carrying adiscovery resource configuration. The discovery resource informationcycle in which the discovery resource configuration may be changed isconfigurable to prevent the D2D-enabled UE from waking up in everydiscovery resource information cycle to receive and decode the PDCCH. Inorder to improve the reliability of the PDCCH, the PDCCH may be repeateda plurality of times in the discovery resource information cycle.

FIG. 8 illustrates a discovery resource configuration using a PDCCHtransmitted a plurality of times according to an embodiment of thepresent disclosure.

Referring to FIG. 8, a PDCCH 820 carrying discovery resource informationmay be transmitted a plurality of times during a repetition interval 810in a discovery resource information cycle (DRC) 800. A DRC 830 startsafter an offset 840 from a time of transmitting a last PDCCH 820 in therepetition interval 810. The offset 840 is needed to allow a time toreceive and process PDCCH information, select resources for discoveryinformation transmission, and build a discovery information packet.

In an embodiment, a DRC, a DRI, and a discovery subframe may beconfigured using an SI message. The DRI and discovery subframe(s)configured using the SI message may be a minimum configuration. Anupdated DRI (extended DRI) and additional discovery subframes areindicated by a PDCCH in every discovery resource information cycle asillustrated in FIGS. 7 and 8. If a D2D-enabled UE fails to decode aPDCCH, it always uses the minimum configuration signaled by the SImessage.

In an embodiment of the present disclosure, a discovery resourceinformation cycle may be aligned with a D2D-enabled UE's idle mode DRXcycle. The discovery information resource cycle is configured to be amultiple of a DRX cycle, as illustrated in FIG. 9.

FIG. 9 illustrates a discovery resource configuration using a PDCCHbased on a DRX cycle according to an embodiment of the presentdisclosure.

Referring to FIG. 9, a discovery resource information cycle 900 startsearlier than a DRC 920 by a DRX cycle 910 and an offset 930 between theDRC 920 and the DRX cycle 910. A last paging occasion in the DRX cycle910 may exist in a last subframe of a last frame included in the DRXcycle 910. Therefore, an additional time, that is, the offset 930 isneeded to process PDCCH information and apply the processed PDCCHinformation to the DRC 920.

In each paging occasion of the DRX cycle 910 at the beginning of thediscovery resource information cycle 900, a PDCCH carrying discoveryresource information may be repeatedly transmitted. Each D2D-enabled UEwakes up in every idle DRX cycle of the D2D-enabled UE and receives anddecodes the PDCCH carrying discovery resource information in its idleDRX cycle which falls in the beginning of the discovery resourceinformation cycle.

In an embodiment of the present disclosure, a discovery resourceinformation cycle may be aligned with a D2D-enabled UE's idle mode DRXcycle. The discovery resource information cycle may or may not be amultiple of a DRX cycle, as illustrated in FIG. 10.

FIG. 10 illustrates a discovery resource configuration using a PDCCHbased on a DRX cycle according to another embodiment of the presentdisclosure.

Referring to FIG. 10, a discovery resource information cycle 1000 startsearlier than a DRC 1020 by X frames 1010 (X is the number of framesincluded in a DRX cycle) and an offset 1030 between the DRC 1020 and theX frames 1010. In each paging occasion during the X frames 1010 at thebeginning of the discovery resource information cycle 1000, a PDCCHcarrying discovery resource information may be repeatedly transmitted.Each D2D-enabled UE wakes up in every idle DRX cycle of the D2D-enabledUE and receives and decodes the PDCCH carrying discovery resourceinformation in its idle DRX cycle which falls in the beginning of thediscovery resource information cycle.

Signaling Discovery Resource Configuration Using PDCCH and SI Message

In an embodiment of the present disclosure, discovery resource may beconfigured in two steps. A discovery resource configuration including aDRC, a DRI, and a discovery subframe may be configured using an SIB inan SI message in a first step and discovery resources in each of thediscovery subframes configured using the SI message may be configureddynamically using a PDCCH in a second step. The aforesaid concept isillustrated in FIG. 11.

FIG. 11 illustrates a discovery resource configuration using an SImessage and a PDCCH according to an embodiment of the presentdisclosure.

Referring to FIG. 11, a PDCCH indicating discovery resources istransmitted in a Downlink (DL) subframe corresponding to each discoverysubframe. The PDCCH indicating discovery resources may be masked with aD2D C-RNTI. The DL subframe carrying the PDCCH for the discoverysubframe is apart from that discovery subframe by an offset 1100. Theoffset 1100 is needed to allow a time to receive and process PDCCHinformation, select resource for discovery informationtransmission/reception, and build a discovery information packet.

A D2D-enabled UE participating in discovery first reads an SI messageand determines a DRC, a DRI, and discovery subframes. The D2D-enabled UEthen receives and decodes a PDCCH masked with a D2D C-RNTI in a DLsubframe corresponding to each discovery subframe during the DRI inevery DRC.

In another embodiment of the present disclosure, a discovery resourceconfiguration including a DRC and a DRI may be configured using an SIBin an SI message in a first step and discovery resources in each ofsubframes in the DRI may be configured dynamically using a PDCCH in asecond step, as illustrated in FIG. 12.

FIG. 12 illustrates a discovery resource configuration using an SImessage and a PDCCH according to another embodiment of the presentdisclosure.

Referring to FIG. 12, a PDCCH indicating discovery resources istransmitted in a DL subframe corresponding to each subframe in aconfigured DRI. The PDCCH indicating discovery resources may be maskedwith a D2D C-RNTI. The DL subframe carrying the PDCCH for the subframein the DRI is apart from that subframe by an offset 1200. The offset1200 is needed to allow a time to receive and process PDCCH information,select resources for discovery information transmission/reception, andbuild a discovery information packet.

A D2D-enabled UE participating in discovery first reads an SI messageand determines a DRC and a DRI. The D2D-enabled UE then receives anddecodes a PDCCH masked with a D2D C-RNTI in the DL subframecorresponding to each subframe during the DRI in every DRC.

In another embodiment of the present disclosure, a discovery resourceconfiguration including a DRC may be configured using an SIB in an SImessage in a first step. Here, a DRI and discovery subframes in the DRImay be configured dynamically using a PDCCH at the beginning of each DRCin a second step. In a third step, discovery resources in each of thediscovery subframes may be configured dynamically by the PDCCH, asillustrated in FIG. 13.

FIG. 13 illustrates a discovery resource configuration using an SImessage and a PDCCH according to another embodiment of the presentdisclosure.

Referring to FIG. 13, a DL subframe 1300 corresponding to a firstsubframe of a DRC indicates a DRI and discovery subframes in the DRI. APDCCH in a DL subframe corresponding to each of the discovery subframesindicates discovery resources in the discovery subframe.

In another embodiment of the present disclosure, a discovery resourceconfiguration including a DRC may be configured using an SIB in an SImessage in a first step. In a second step, a DRI may be configureddynamically using a PDCCH at the beginning of each DRC. In a third step,discovery resources in each of subframes in the DRI may be configureddynamically by the PDCCH, as illustrated in FIG. 14.

FIG. 14 illustrates a discovery resource configuration using an SImessage and a PDCCH according to another embodiment of the presentdisclosure.

Referring to FIG. 14, a DL subframe 1400 corresponding to a firstsubframe of a DRC indicates a DRI. A PDCCH in a DL subframecorresponding to each of subframes in the DRI indicates discoveryresources in the subframe.

Method for Updating Discovery Resources

A DRC includes discovery resources. D2D-enabled UEs participating indiscovery use these discovery resources in a contention-based manner.The discovery resources may be configured based on a discovery load bythe network. The network may change the discovery resources in the DRCbased on the discovery load. The network may determine the discoveryload in one of the following methods.

a) A D2D-enabled UE which wants to transmit discovery informationmonitors discovery resources in a DRC to determine available discoveryresources (that is, discovery resources not used by other D2D-enabledUEs). The D2D-enabled UE determines whether discovery resources areavailable by measuring a signal energy or decoding a discovery channeltransmitted in each discovery resource. When the D2D-enabled UE fails tofind available resources for discovery for a predetermined time period,it transmits a discovery resource update message/indication to thenetwork (that is, a BS). The discovery resource update message mayinclude information about resources (for example, information about anumber of resources) that the UE needs for discovery. This message maybe an indication to the network to increase discovery resources. Thenetwork may increase discovery resources based on the number of UEs fromwhich the network has received the above message. A time intervalbetween two discovery resource update messages/indications transmittedby a D2D-enabled UE may be defined to avoid frequent transmissions ofthe discovery resource update message/indication.

b) A D2D-enabled UE which wants to transmit discovery informationmonitors discovery resources in a DRC to determine available discoveryresources (that is, discovery resources not used by other D2D-enabledUEs). When the D2D-enabled UE determines that the number of availablediscovery resources is less than a predefined threshold, it transmits adiscovery resource update message/indication to the network.Alternatively or additionally, when the D2D-enabled UE determines thatthe number of unavailable (that is, used) resources is greater than apredefined threshold, it transmits a discovery resource updatemessage/indication to the network. This may be an indication to thenetwork to increase discovery resources. The D2D-enabled UE determineswhether discovery resources are available by measuring a signal energyor decoding a discovery channel transmitted on each discovery resource.The predefined threshold may be configured by the network. A timeinterval between two discovery resource update messages/indicationstransmitted by a D2D-enabled UE may be defined to avoid frequenttransmissions of the discovery resource update message/indication. In anembodiment, a plurality of threshold levels (for example, high, low, andmedium) may be defined instead of one threshold level. In an embodiment,a D2D-enabled UE may periodically transmit information about alreadyused or available resources based on its sensing.

c) A D2D-enabled UE which wants to transmit discovery informationmonitors discovery resources in a DRC to determine available discoveryresources (that is, discovery resources not used by other D2D-enabledUEs). When the D2D-enabled UE determines that the number of availablediscovery resources is greater than a predefined threshold, it transmitsa discovery resource update message/indication to the network.Alternately or additionally, when the D2D-enabled UE determines that thenumber of unavailable (that is, used) resources is less than apredefined threshold, it transmits a discovery resource updatemessage/indication to the network. This may be an indication to thenetwork to decrease discovery resources. The D2D-enabled UE determineswhether discovery resources are available by measuring a signal energyor decoding a discovery channel transmitted in each discovery resource.The predefined threshold may be configured by the network. A timeinterval between two discovery resource update messages/indications by aD2D-enabled UE may be defined to avoid frequent transmissions of thediscovery resource update message/indication. In an embodiment, aplurality of threshold levels (for example, high, low, and medium) maybe defined instead of one threshold level.

d) A BS may measure a signal energy or decode a discovery channeltransmitted in discovery resources and determine the utilization of thediscovery resources. Based on the determined utilization and/orfeedbacks from D2D-enabled UEs, the network may increase or decrease thediscovery resources.

e) A D2D-enabled UE which is monitoring discovery resources to receivediscovery information may assist the network in updating the discoveryresources. The monitoring D2D-enabled UE monitors all discoveryresources. Based on the result of receiving and decoding a discoverychannel in discovery resources, the monitoring UE knows how muchdiscovery resources are used and how much discovery resources are notused. When the D2D-enabled UE monitoring discovery resources determinesthat the number of used resources is greater than a predefinedthreshold, it transmits a discovery resource update message/indicationto the network. In an embodiment, a plurality of threshold levels (forexample, high, low, and medium) may also be defined instead of onethreshold level. In an embodiment, the D2D-enabled UE may periodicallytransmit information about already used or available discovery resourceswithout comparing the number of the resources with a predefinedthreshold.

A time interval between two discovery resource updatemessages/indications transmitted by the D2D-enabled UE may be defined toavoid frequent transmissions of the discovery resource updatemessage/indication.

To avoid transmissions of the discovery resource updatemessage/indication from a plurality of D2D-enabled UEs receiving thediscovery information, different D2D-enabled UEs may be configured totransmit discovery resource update messages/indications in differentDRCs. Association of a D2D-enabled UE with a DRC for transmitting adiscovery resource update message/indication may be based on itsidentity.

In an embodiment, one or more fixed time frequency resources may bereserved for transmitting a discovery resource update message/indicationto a BS. A plurality of threshold levels (for example, high, low, andmedium) may be defined instead of one threshold level. In this case,there is one-to-one mapping between the fixed time frequency resourcesand discovery resource update messages/indications specific to thethreshold levels. An RB pair(s) similar to a PUCCH may be reserved in asubframe for transmitting a discovery resource updatemessage/indication. Physical layer parameters (modulation, coding, andthe like) for transmission in these reserved RB pair(s) may also befixed. In an embodiment, these parameters are the same as a discoverychannel. In another embodiment, these parameters may be the same as arandom access channel. An RB pair(s) of a discovery subframe or anon-discovery subframe may be reserved. The RB pair(s) may be reservedperiodically. In one example, an RB pair(s) may be reserved in everyDRC. In another example, an RB pair(s) may be reserved once every ‘n’DRCs. Herein, ‘n’ may be larger than 1. Even if a plurality ofD2D-enabled UEs transmit the messages/indications simultaneously inthese resources, there will not be any problem becausemessage/indication contents and physical layer parameters (modulation,coding, and the like) are fixed and the same for all UEs. In anembodiment, an access channel sequence may be transmitted in fixed timeand frequency resources, instead of in a message. In an embodiment, oneor more access channel sequences may be reserved for transmission infixed time and frequency resources, instead of in a message. One accesschannel sequence may be used for a specific threshold levelindication/message.

In another embodiment, the network may determine a discovery load asfollows. A D2D-enabled UE which wants to transmit discovery informationtransmits a message to a BS. The message may include information about anumber of discovery resources that the D2D-enabled UE will use. Themessage may also include information about a time period during whichthe D2D-enabled UE will use the discovery resources. When it stopstransmitting discovery information, the D2D-enabled UE may transmit amessage to the BS. This message may not be needed if a time period isalready indicated in the message transmitted to the BS when the UEstarted transmitting the discovery information. In an embodiment, the BSforwards these messages received from the UE to a centralizedcoordinator. The centralized coordinator updates discovery resources andinforms all BSs of the updated discovery resources. The centralizedcoordinator may perform the update periodically instead of performingthe update every time a message is received from a UE. In anotherembodiment, the BS may perform the discovery resource update based on amessage(s) received from a UE(s).

Resource Selection by D2D-Enabled UE for Transmitting DiscoveryInformation

A D2D-enabled UE transmitting discovery information needs to know timeand frequency resources that it needs to use for transmitting thediscovery information. The following options may be used for theselection of resources for transmitting discovery information.

1. Contention-based resource selection from among configured discoveryresources: In order to receive a dedicated resource assignment, theD2D-enabled UE has to transmit a request to a camped cell. TheD2D-enabled UE transmitting the discovery information may be mobile innature. Because of the mobility of D2D-enabled UEs, their camped cellmay change often and thus the D2D-enabled UE has to transmit a requestto a new cell almost every DRC. This leads to a significant signalingoverhead in the system. Thus, a contention-based resource selectionprotocol may be preferred for mobile D2D-enabled UEs. A mobileD2D-enabled UE uses the contention-based resource selection protocol forselecting resources from among discovery resources configured by thenetwork. In one method, the contention-based protocol includes a methodfor randomly selecting discovery resources from among a plurality ofdiscovery resources, for transmitting discovery information. In anembodiment, a D2D-enabled UE may use a maximum number of ‘n’ discoveryresources per DRC. This may help in reducing collisions. The parameter‘n’ is configured by the network. A default value of ‘n’ may be set to1.

2. Dedicated resource assignment: All D2D-enabled UEs may not be highlymobile. Dedicated time and frequency resources from among allocated timefrequency resources for D2D direct discovery may be allocated to aD2D-enabled UE(s) with no mobility (that is, stationary). Theno-mobility may be determined based on user subscriptions by thenetwork. For example, D2D-enabled UEs installed in commercialestablishments for advertisements may be stationary. For a plurality ofstationary D2D-enabled UEs, the network may prioritize dedicatedresource assignments based on paid subscription fees. A D2D-enabled UEmay indicate that it is stationary when it registers with the network.Dedicated resources are allocated from among discovery resourcesconfigured by the network. The dedicated resources may be allocated in asemi-static manner. If a time duration of the dedicated resourcesexpires, the D2D-enabled UE may make the request again. Dedicateddiscovery resources and non-dedicated discovery resources may exist ineach DRC. Alternatively, some DRCs may be configured for dedicatedresource assignment only.

Dedicated resources may be allocated to one or more of the followingUEs:

a) stationary UEs installed in commercial establishments;

b) premium UEs paying more subscription or usage fees;

c) UEs in connected mode;

d) UEs with discovery applications requiring high quality of service;and

e) UEs which need to be tracked by a BS for lawful interception. The BSshould allocate a type 2 discovery subframe for lawful interception suchthat it is not followed by a subframe in which UE to BS transmission isscheduled. The BS uses different timings to receive UE to BStransmissions and discovery transmissions of a UE.

If the dedicated resources can be allocated to D2D-enabled UEs fortransmitting discovery information, the BS should broadcast discoveryresource information as follows.

A discovery resource signaling basically indicates which subframes haveresources for discovery and which RBs are for discovery in each of thesesubframes. The BS indicates which discovery resources are common (non-UEspecific) and which discovery resources are dedicated. In an embodiment,all RBs reserved for discovery in a subframe may be for common usage orfor dedicated discovery usage. This means that the discovery subframehas either common discovery resources or dedicated discovery resourcesand not both. The network signals which subframe has common discoveryresources and which subframe has dedicated discovery resources. Inanother embodiment, some of the RBs reserved for discovery in a subframemay be for common usage or for dedicated discovery usage. This meansthat the discovery subframe has both common discovery resources anddedicated discovery resources. The network signals which RBs reservedfor discovery are common discovery resources and which RBs reserved fordiscovery are dedicated discovery resources. In another embodiment, aDRI may be partitioned into a dedicated discovery zone and a commondiscovery zone in the time domain. All discovery resources reserved insubframes corresponding to the dedicated discovery zone are dedicateddiscovery resources. All discovery resources reserved in subframescorresponding to the common discovery zone are common discoveryresources. In another embodiment, a DRI may be partitioned into adedicated discovery zone and a common discovery zone in the frequencydomain.

A BS may signal a pool of type 1 discovery resources as a discoveryresource transmission (Tx) Pool. The BS signals the summation of a poolof type 1 discovery resources and a pool of type 2 discovery resourcesas a discovery resource reception (Rx) pool. Alternately, the BS maysignal a pool of type 1 discovery resources. BS may also signal a poolof Type 2 discovery resources. The pool of type 1 discovery resourcesmay be used by the UE for transmitting. Summation of a pool of type 1discovery resources and a pool of type 2 discovery resources may be usedby the UE for reception.

If a UE transmitting discovery information has not been allocateddiscovery resources, it does not use discovery resources marked asdedicated discovery resources. The UE uses only discovery resourcesmarked as common discovery resources.

If a UE is in connected mode, communicating with a BS, and transmitsdiscovery information, the following rules may be applied for the UE totransmit discovery information and UL signals to the BS.

a) A D2D-enabled UE does not transmit a PUCCH and a D2D transmission inthe same subframe because the D2D UE uses a DL timing for D2Dtransmissions whereas a timing based on UL synchronization is used forPUCCH transmissions. In an embodiment, the BS schedules PUCCHs such thata D2D-enabled UE in connected mode may not have to transmit a PUCCH in aD2D subframe. The D2D-enabled UE indicates to the BS whether it wants totransmit D2D transmissions while communicating with the BS. In the caseof a dedicated discovery resource assignment, the BS may allocatediscovery resources to the UE in a subframe in which a PUCCHtransmission is not scheduled. In another method, if the D2D-enabled UEhas to transmit a PUCCH in a D2D subframe, the D2D-enabled UE does nottransmit D2D transmissions in the D2D subframe.

b) A D2D-enabled UE does not transmit a D2D transmission in subframe ‘x’and a transmission (e.g. PUCCH/PUSCH/D2D Data packets) wherein timingadvanced (TA) is applied in subframe ‘x−1’. In an embodiment, the BStakes care of this by scheduling such that a transmission based on TA ina subframe following the subframe with non TA based transmission may beavoided. The D2D-enabled UE indicates to the BS whether it wants totransmit D2D-transmissions while communicating with the BS. In the caseof a dedicated discovery resource assignment, the BS may allocatediscovery resources to the UE in a subframe which is not preceded by asubframe in which a PUCCH/PUSCH transmission is scheduled. In anotherembodiment, the UE does not perform a D2D transmission in subframe ‘x’if it has to perform a transmission (e.g. PUCCH/PUSCH/D2D Data packets)wherein TA is applied in subframe ‘x+1’. UE maintains subframe timingwith respect to a DL signal received from the BS. For UL transmissionthe BS provides a value by which the UE should advance the timing for ULtransmission. Applying TA in subframe ‘x+1’ means that if subframe ‘x+1’starts at time t=t1 based on a DL signal received from the BS then itstarts transmission corresponding to subframe ‘x+1’ at t=t1-timingadvanced. In an embodiment, the UE does not perform a D2D transmissionin subframe ‘x’ if it has to perform a transmission (e.g.PUCCH/PUSCH/D2D Data packets) wherein the TA>‘p’ and an orthogonalfrequency-division multiplexing (OFDM) symbols duration is applied insubframe ‘x+1’, where ‘p’ is a number of OFDM symbols at the end ofsubframe ‘x’ which are not used for D2D transmission in subframe ‘x’.

Resource Selection by D2D-Enabled UE for Receiving Discovery Information

If the contention-based resource selection protocol is used, aD2D-enabled UE monitoring discovery information does not know resourcesselected by a D2D-enabled UE transmitting the discovery information. Inan embodiment, therefore, the D2D-enabled UE monitoring the discoveryinformation monitors all discovery resources (common as well asdedicated) configured for D2D direct discovery.

In an embodiment, if the discovery information transmission is targetedto a specific D2D-enabled UE, the transmitting D2D-enabled UE maydetermine resources from among a plurality of resources by hashingresource indices with a target D2D identifier (ID). In this case, theD2D-enabled UE receiving the discovery information selects the resourcesby hashing with its D2D ID.

In an embodiment, the transmitting D2D-enabled UE may determineresources from among a plurality of resources by hashing with its D2DID. In this case, the D2D UE receiving the discovery information selectsthe resources by hashing with a D2D ID which it wants to monitor.

If dedicated resources are used by the D2D-enabled UE transmitting thediscovery information, one or more D2D-enabled UEs monitoring thediscovery information may know the discovery resources through thenetwork (for example, a proximity service (ProSe) server). The BS or UEmay inform the ProSe Server of the dedicated resources. However, this ispossible only for the transmitting D2D-enabled UE(s) with no mobility.

In an embodiment, for a simple and efficient design, the D2D-enabled UEmonitoring the discovery information monitors all discovery resourcesconfigured for D2D direct discovery.

Some of the methods of signaling discovery resources in the foregoingmethods are as follows. In all these options, some or all listedparameters may be transmitted to signal a resource configuration.

TABLE 1 Options Parameters of Discovery Resource Configuration Option1 1) DiscoveryResourceCycle; Note: Some specific values for discoveryresource cycle can be pre defined and index can be used to indicate insignaling instead of absolute value of discovery resource cycle. Note:SFN mod DiscoveryResourceCycle = DiscoveryResourceCycleOffset. ‘SFN’ issystem frame number of start of Discovery Resource Cycle; OR (SFN * 10 +sub frame number) mod DiscoveryResourceCycle =DiscoveryResourceCycleOffset. ‘SFN’ is system frame number; DiscoveryResource Cycle starts at subframe number in SFN. 2)DiscoveryResourceCycleOffset 3) NumNonDiscoverySF; Note: This can be abit map or absolute number 4) ResourceAllocationSupportedTypes (Type 1and/or Type 2) Note: Indicates whether network or cell supports Type 1and/or Type 2 resource allocation mechanisms. Type 1 is contention basedresource allocation and Type 2 is dedicated resource allocation. 5) TXResource Pool: Resources (Type 1) used by transmitting UE a. NumTxSF; b.Discovery Resources in each discovery subframe amongst the ‘NumTxSF’subframes in the beginning of Discovery Resource Cycle; Note: Nondiscovery subframes in ‘NumTxSF’ are determined based on parameterNumNonDiscoverySF 6) RX Resource Pool: a. NumRxSF; b. DiscoveryResources in each discovery subframe amongst the ‘NumRxSF’ subframes inbeginning of Discovery Resource Cycle; Note: Non discovery subframes in‘NumRxSF’ are determined based on parameter   NumNonDiscoverySF    Note: NumRxSF <= NumTxSF Option 2 1) DiscoveryResourceCycle; 2)DiscoveryResourceCycleOffset 3) NumNonDiscoverySF; 4)ResourceAllocationSupportedTypes (Type 1 and/or Type 2) 5) Type 1Resource Pool: a. NumType1SF; b. Discovery Resources in each discoverysubframe amongst the ‘NumType1SF’ subframes in the beginning ofDiscovery Resource Cycle; Note: Non discovery subframes in ‘NumType1SF’are determined based on parameter     NumNonDiscoverySF 6) Type 2Resource Pool: a. NumType2SF; b. Discovery Resources in each discoverysubframe amongst the ‘NumType2SF’ subframes following ‘NumType1SF’subframes in the Discovery Resource Cycle or from the beginning ofdiscovery resource cycle; Note: Non discovery subframes in ‘NumType2SF’are determined based on parameter     NumNonDiscoverySF Note: TXResource Pool = Type 1 Resource Pool; Note: RX Resource Pool = Type 1Resource Pool + Type 2 Resource Pool;

TABLE 2 Options Parameters of Discovery Resource Configuration Option3 1) DiscoveryResourceCycle; 2) DiscoveryResourceCycleOffset 3)DiscoveryResourceDuration or NumSFs 4) ResourceAllocationSupportedTypes(Type 1 and/or Type 2) 5) DiscoveryNonDiscoverySF (bitmap of sizeNumSFs): Indicate which subframe(s) out of ‘NumSFs’ has discoveryresources OR  NumNonDiscoverySF;   An ‘offset’ can also be added asadditional parameter here. It is offset from beginning of discoveryresource cycle and first subframe indicated by NumNonDiscoverySF orDiscoveryNonDiscoverySF 6) Discovery Resources a. For each of thesubframe having discovery resources indicate i. Indicate TX discoveryresources (i.e. PRBs) ii. Indicate RX Discovery resources (i.e. PRBs) ORb. For each of the subframe having discovery resources i. Indicate theType 1 discovery resources (i.e. PRBs): ii. Indicate the Type 2discovery resources (i.e. PRBs); Note: Non discovery subframes ‘aredetermined based on parameter     NumNonDiscoverySF      orDiscoveryNonDiscoverySF Note: Every subframe may have Type 1 and/or Type2 discovery resources Note: TX Resource Pool = Type 1 Resource Pool:Note: RX Resource Pool = Type 1 Resource Pool + Type 2 Resource Pool;

TABLE 3 Options Parameters of Discovery Resource Configuration Option4 1) DiscoveryResourceCycle; 2) DiscoveryResourceCycleOffset 3)ResourceAllocationSupportedTypes (Type 1 and/or Type 2) 4)RadioFrameNumber: Radio frame number(s) in discovery resource cyclewhich has discovery resources a. SFNum: Subframe numbers(for each radioframe number indicated above) which has discovery resources Note: Inalternate method only subframe number may be indicated wherein subframesare logically numbered sequentially from beginning of discovery resourcecycle. 5) Discovery Resources c. For each of the subframe (indicated byRadioFrameNumber and SFNum) having discovery resources indicate i.Indicate TX discovery resources (i.e. PRBs) ii. Indicate RX Discoveryresources (i.e. PRBs) OR d. For each of the subframe having discoveryresources i. Indicate the Type 1 discovery resources (i.e. PRBs): ii.Indicate the Type 2 discovery resources (i.e. PRBs): Note: if a subframehas only one type of PRBS and all PRBs for discovery then just indicatetype of resource in the subframe. PRBs are not indicated.

TABLE 4 Options Parameters of Discovery Resource Configuration. Option5 1) DiscoveryResourceCycle; 2) DiscoveryResourceCycleOffset 3)ResourceAllocationSupportedTypes (Type 1 and/or Type 2) 4) Type 1Resource Pool: a. Offset (this can be in number of subframes of frames.Alternately this can he starting radio frame number and/or subframenumber) b. NumType1SF; (These many subframes are there after/from an‘offset’ from beginning of discovery resource cycle.) c. DiscoveryResources in each discovery subframe amongst the ‘NumType1SF’ subframes;d. Bitmap to indicate discovery and non-discovery subframe in NumType1SF5) Type 2 Resource Pool: a. Offset (this can be in number of subframesof frames. Alternately this can be starting radio frame number and/orsubframe number) b. NumType2SF; (These many subframes are there after an‘offset’ from, beginning of discovery resource cycle.) c. DiscoveryResources in each discovery subframe amongst the ‘NumType2SF’ subframesd. Bitmap to indicate discovery and non-discovery subframe in NumType1SFNote: TX Resource Pool = Type 1 Resource Pool; Note: RX Resource Pool =Type 1 Resource Pool + Type 2 Resource Pool;

TABLE 5 Options Parameters of Discovery Resource Configuration Option6 1) DiscoveryResourceCycle; 2) DiscoveryResourceCycleOffset 3)ResourceAllocationSupportedTypes (Type 1 and/or Type 2) 4) Type 1Resource Pool: a. RadioFrameNumbers: Radio frame number(s) in discoveryresource cycle which has discovery resources i. SFNums: Subframenumbers(for each radio frame number indicated above) which has discoveryresources 5) Type 2 Resource Pool: a. RadioFrameNumbers: Radio framenumber(s) in discovery resource cycle which has discovery resources i.SFNums: Subframe numbers(for each radio frame number indicated above)which has discovery resources Note: TX Resource Pool = Type 1 ResourcePool; Note: RX Resource Pool = Type 1 Resource Pool + Type 2, ResourcePool;

FIG. 15 is a flowchart illustrating an operation of a BS according to anembodiment of the present disclosure.

Referring to FIG. 15, the BS determines discovery resource periodicity,a DRI size, discovery subframes in a DRI and discovery resource blocksin discovery subframes for each of the one or more discovery resourcepools in operation 1500 and generates information indicating thedetermined discovery resource periodicity, DRI size, the determineddiscovery subframes in the DRI and discovery resource blocks indiscovery subframes for each of the one or more discovery resource poolsin operation 1502.

In operation 1504, the BS generates discovery resource configurationinformation by including the generated information in at least one of anSI message, a PDCCH, and a DL-SCH. The BS then transmits the generateddiscovery resource configuration information in operation 1506.

FIG. 16 is a flowchart illustrating an operation of a UE according to anembodiment of the present disclosure.

Referring to FIG. 16, the UE receives discovery resource configurationinformation from a BS and decodes the received discovery resourceconfiguration information in operation 1600. In operation 1602, the UEdetects information indicating discovery resource periodicity, a DRIsize, discovery subframes in a DRI and discovery resource blocks indiscovery subframes for each of the one or more discovery resource poolsfrom the decoded discovery resource configuration information.

The UE determines discovery resources based on the detected informationin operation 1604 and performs discovery using the detected resources inoperation 1606.

FIG. 17 is a block diagram of a BS according to an embodiment of thepresent disclosure.

Referring to FIG. 17, the BS includes a controller 1700, a transmitter1702, a receiver 1704, and a memory 1706. The controller 1700 controlsthe transmitter 1702, the receiver 1704, and the memory 1706, andperforms BS operations according to the foregoing embodiments of thepresent disclosure. The transmitter 1702 performs a transmissionoperation such as transmission of discovery resource configurationinformation to a UE. The receiver 1704 receives data and messages fromthe UE. The memory 1706 stores various types of information that aregenerated by a BS operation or that are required.

FIG. 18 is a block diagram of a UE according to an embodiment of thepresent disclosure.

Referring to FIG. 18, the UE includes a controller 1800, a transmitter1802, a receiver 1804, and a memory 1806. The controller 1800 controlsthe transmitter 1802, the receiver 1804, and the memory 1806, andperforms UE operations according to the foregoing embodiments of thepresent disclosure. The transmitter 1802 performs a transmissionoperation to a BS and the receiver 1804 performs a reception operationsuch as reception of discovery resource configuration information fromthe BS. The memory 1806 stores various types of information that aregenerated by a UE operation or that are required.

The proposed method and apparatus for transmitting and receivingresource allocation information in a wireless communication system maybe implemented as computer-readable code in a computer-readablerecording medium. The computer-readable recording medium may include anykind of recording device storing computer-readable data. Examples of therecording medium may include read only memory (ROM), random accessmemory (RAM), optical disk, magnetic tape, floppy disk, hard disk,non-volatile memory, and the like, and may also include the medium thatis implemented in the form of carrier waves (for example, transmissionover the Internet). In addition, the computer-readable recording mediummay be distributed over the computer systems connected over the network,and computer-readable codes may be stored and executed in a distributedmanner.

As is apparent from the foregoing description, since resources for D2Ddiscovery are efficiently configured, the D2D discovery can be performedwithout affecting communication of legacy UEs and a UL HARQ operation.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

1-37. (canceled)
 38. A method of a base station (BS) in a communicationsystem, the method comprising: generating information related toresources for discovery, the information includes subframe bitmapinformation; and transmitting the information.
 39. The method of claim38, wherein the information further includes at least one of resourceperiod information, repetition information and physical resource block(PRB) information.
 40. The method of claim 38, wherein the informationrelates to a pool of resources for discovery.
 41. The method of claim39, wherein the resource period information relates to a duration forallocating of the resources.
 42. The method of claim 39, wherein therepetition information relates to the number of times a bitmap occurswithin the duration for allocating of the resources.
 43. The method ofclaim 38, wherein the information further includes information relatedto a set of time/frequency resources used for discovery.
 44. The methodof claim 39, wherein the PRB information relates to PRB on a subframefor the discovery in a duration for allocating of the resources, andincludes PRB start index and PRB end index.
 45. The method of claim 38,wherein the subframe bitmap information relates to a bitmap of size ‘N’bits, and each bit of the bitmap corresponds to a subframe, and whereinthe bitmap indicates the subframe is used for the discovery.
 46. Amethod of a user equipment (UE) in a communication system, the methodcomprising: receiving information related to resources for discovery,the information includes subframe bitmap information; and performingdiscovery based on the information.
 47. The method of claim 46, whereinthe information further includes at least one of resource periodinformation, repetition information and physical resource block (PRB)information.
 48. The method of claim 46, wherein the information relatesto a pool of resources for discovery.
 49. The method of claim 47,wherein the resource period information relates to a duration forallocating of the resources.
 50. The method of claim 47, wherein therepetition information relates to the number of times a bitmap occurswithin the duration for allocating of the resources.
 51. The method ofclaim 46, wherein the information further includes information relatedto a set of time/frequency resources used for discovery.
 52. The methodof claim 47, wherein the PRB information relates to PRB on a subframefor the discovery in a duration for allocating of the resources, andincludes PRB start index and PRB end index.
 53. The method of claim 46,wherein the subframe bitmap information relates to a bitmap of size ‘N’bits, and each bit of the bitmap corresponds to a subframe, and whereinthe bitmap indicates the subframe is used for the discovery.
 54. A basestation (BS) in a communication system, the BS comprising: at least oneprocessor configured to generate information related to resources fordiscovery, the information includes subframe bitmap information; and atransceiver configured to transmit the information.
 55. The BS of claim54, wherein the information further includes at least one of resourceperiod information, repetition information and physical resource block(PRB) information.
 56. The BS of claim 54, wherein the informationrelates to a pool of resources for discovery.
 57. The BS of claim 55,wherein the resource period information relates to a duration forallocating of the resources.
 58. The BS of claim 55, wherein therepetition information relates to the number of times a bitmap occurswithin the duration for allocating of the resources.
 59. The BS of claim54, wherein the information further includes information related to aset of time/frequency resources used for discovery.
 60. The BS of claim55, wherein the PRB information relates to PRB on a subframe for thediscovery in a duration for allocating of the resources, and includesPRB start index and PRB end index.
 61. The BS of claim 54, wherein thesubframe bitmap information relates to a bitmap of size ‘N’ bits, andeach bit of the bitmap corresponds to a subframe, and wherein the bitmapindicates the subframe is used for the discovery.
 62. A user equipment(UE) in a communication system, the UE comprising: a transceiverconfigured to receive information related to resources for discovery,the information includes subframe bitmap information; and at least oneprocessor configured to perform discovery based on the information. 63.The UE of claim 62, wherein the information further includes at leastone of resource period information, repetition information and physicalresource block (PRB) information.
 64. The UE of claim 62, wherein theinformation relates to a pool of resources for discovery.
 65. The UE ofclaim 63, wherein the resource period information relates to a durationfor allocating of the resources.
 66. The UE of claim 63, wherein therepetition information relates to the number of times a bitmap occurswithin the duration for allocating of the resources.
 67. The UE of claim62, wherein the information further includes information related to aset of time/frequency resources used for discovery.
 68. The UE of claim63, wherein the PRB information relates to PRB on a subframe for thediscovery in a duration for allocating of the resources, and includesPRB start index and PRB end index.
 69. The UE of claim 62, wherein thesubframe bitmap information relates to a bitmap of size ‘N’ bits, andeach bit of the bitmap corresponds to a subframe, and wherein the bitmapindicates the subframe is used for the discovery.